The exit comes amid reports that there was disagreement within the administration over Trump’s decision to host a now-cancelled meeting with Taliban leaders at Camp David.

Bolton, a leading foreign policy hawk, was widely known to have pressed the president for a harder line on issues such as North Korea. Bolton, also a chief architect of Trump’s strong stance on Iran, had advocated a tougher approach on Russia and Afghanistan.

Trump had sometimes joked about Bolton’s image as a warmonger, reportedly saying in one Oval Office meeting that “John has never seen a war he doesn’t like.”

Bolton was scheduled to hold a press briefing with Secretary of State Mike Pompeo and Treasury Secretary Steven Mnuchin later on Tuesday.

Bolton was Trump’s third national security adviser after Michael Flynn and HR McMaster.